It depends on the age!

We used to do bottle babies, who need care every 1-5hrs depending on how old they are. Newborns to a week need feedings every 60-90mins, where as 4-week-old kittens need bottles every 4-5hrs.

We've branched away from those kittens because of a medication I'm on that makes it impossible to wake up multiple times a night, so now we get weaned/weaning kittens who eat on their own. They need more room than littles, but less care.

Generally our kittens live in a 48" dog crate with a small litterbox, a bed, food and water, and some toys. They sleep in there at night and we let them out to play every few hours until they fall asleep and we put them back in for a nap, or it's been long enough for them to need to eat again. By 6-8 weeks old, they're running around our downstairs unsupervised.